A local activation time of a particular area of the heart is the time at which the wavefront of electrical propagation passes through the area. A local activation time is typically measured from a particular reference time, such as a particular point in time in the QRS complex of a body-surface electrocardiogram (ECG) recording.
Some types of cardiac arrhythmia are caused by the electrical activation of cardiac tissue over two or more separate activation pathways having different respective rates of propagation.
Cárdenes, Rubén, et al., “Estimation of electrical pathways finding minimal cost paths from electro-anatomical mapping of the left ventricle,” International Workshop on Statistical Atlases and Computational Models of the Heart, Springer, Berlin, Heidelberg, 2013, presents a method to find electrical pathways using minimal cost paths computations on surface maps.